Submarine Appliances And Their Uses
Deep Sea Diving, &c., &c.

DIVING BELLS. There are two forms of Diving Bell in use at the present day—the Air-Lock, or Caisson Bell, and the ordinary, or what may be called the Smeaton Bell. The latter is the more generally employed by reason of its greater simplicity and mobility, and its lower cost. For a considerable time the use of diving bells was prac- tically abandoned, but during the past ten years or so they have again come into favour. This reaction has undoubtedly been brought about by the improvements that have been made in the construction of the bells themselves, the better air supply and consequently better ventilation, the introduction of the electric light, which has displaced the old method of lighting with oil lamps, candles, etc., the carbon from which was inhaled by the bell-men and seriously affected their health, and the adoption of the telephone, which saves so much time in the working of the bell. The Air-Lock Bell is constructed of mild steel plates. The working chamber is usually rectangular in form, and weighted internally or externally with cast- iron kentledge to overcome its displacement. The interior is fitted with tele- phonic apparatus communicating between bell and crane room, and between bell and air-compressor room. Two or three electric lamps are fixed in the roof, whilst there arc several portable lamps for the bcll-mcn. Running from the roof of the bell to above the water surface is a steel shaft of from 30 inches to 36 inches in diameter surmounted by an air-lock. In some cases two shafts, each with its air-lock, are fitted—one for workmen, the other for materials. Inside the shaft is fitted an iron ladder by which the bell-men descend and ascend. The electric light cable and telephone wires arc also led down the shaft. The bell is worked either from a gantry (see photos on pages 70, 71 and 73), or what is found to be more convenient, from a specially constructed barge (see page 74) having a well in the centre through which it is raised and lowered by means of wire ropes over sheaves fitted to a superstructure erected over the well. The barge carries the necessary boilers, air compressors for sup- plying air to the bell and for working pneumatic tools, etc., hoisting engines, mooring winches, electric light engine, etc. The Ordinary Bell is really the lower part—i.e., the working chamber—of the air-lock bell without the shaft and locks. The air pipe is connected to a non-return inlet valve fitted in the roof, and lenses are sometimes fitted in the roof, but more often in the ends of the bell. (See photos, pages 70 and 73.) When asking for estimates for Diving Bells, the following particulars should be supplied, viz ;— (a) Dimensions of bell, or number of men it is proposed should work in it. (ô) Maximum depth of water. (c) Capacity of lifting power available for lowering and raising bell. 69